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Digital Multimeter - Blowing Fuses

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  • Member since
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  • From: Dearborn Station
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Digital Multimeter - Blowing Fuses
Posted by richhotrain on Tuesday, April 28, 2015 7:51 AM

I have a Radio Shack 42-Range Digital Meter, #22-811.

It has a 500mA, 250V, ceramic fuse (Cat. No. 27-1070)

When I first bought it a few years back, it seemed to work fine, but one day it started acting erratically, so I checked the fuse, it was blown, so I replaced it.

Tried to use the meter last night and the replacement fuse was blown.

I have read that a ceramic fuse in a multimeter should not blow except as a result of "operational error".  Let me say, that I have never dropped the meter or otherwise mishandled it.  The only testing that I do with it is on my layout, check voltage, ohms, continuity.

Do I have a lemon?  Should I buy some more fuses?   Or, should I just buy a new meter?

Rich

Alton Junction

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  • From: Reading, PA
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Posted by rrinker on Tuesday, April 28, 2015 7:54 AM

 You aren't changing the measurement selection while the leada are attached to a circuit, are you? Or having it continuity and touching the probes to a live circuit? Not much else would blow the fuse - exceeding 500ma in the ma range would do it as well. If it has a high amp range, like up to 10 amps, there's usually a different place to plug the positive probe into, and a seperate (or in some cases no) fuse for that.

                    --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by richhotrain on Tuesday, April 28, 2015 8:13 AM

None of the above.

I did check the fuse for continuity to confirm that it is blown.

The two probes are correctly connected, the meter is set for voltage, the buttons are set to read AC and V.

My layout is powered by DCC, 5 amps, output around 13.5 volts.

I just fashioned a brass jumper, in the tradition of my grndfather plugging pennies in place of blown fuses, and I get the meter to work.

Now what?

Rich

Alton Junction

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Posted by maxman on Tuesday, April 28, 2015 8:26 AM

Harbor Freight.  Multimeter free with coupon and any purchase, plus a 20% off coupon. Bought one of those throw away knives they sell for 30 cents as the "any purchase".  Used the 20% off coupon on the knife.  So 24 cents got me the knife and the meter.

  • Member since
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  • From: Bedford, MA, USA
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Posted by MisterBeasley on Tuesday, April 28, 2015 8:38 AM

Yup.  New meter.  You'll love it.

It takes an iron man to play with a toy iron horse. 

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Posted by RR_Mel on Tuesday, April 28, 2015 9:53 AM

Rich
 
Multi meters have current shunts, one for each current range.  If you accidently overloaded the meter it could have damaged one of the shunts.  A damaged or open shunt will allow more current through to the meter blowing the fuse.  The fix would be the Harbor Freight meter.   We all do it sooner or later.  I’m a long time techno weenie and I have tossed several HF meters too.  If you’re using an HF meter it helps to put a bright dob of paint on the selector knob so that you don’t accidently select the 10 amp range when you want to use the 20 volt range.  Saves a lot of headaches.
 
HF Meter
 
I added the picture with my white dot.  Really helps me!
 
Mel
  • Member since
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  • From: Vancouver Island, BC
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Posted by selector on Tuesday, April 28, 2015 9:54 AM

[...with my arm around your shoulders and using a fatherly tone...]

It's hard to say good-bye to an old friend.

Crying

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Posted by mlehman on Tuesday, April 28, 2015 10:25 AM

Yeah, I agree. Time for a new meter if it's not something obvious that you would have found in your inspectiosn already. Two options. Go cheap. I have a HF meter I got free IIRC several years ago. It works well, but I would feel no pain if it went belly up.

On the other hand, I also have a "better" tradesmen model I bought when I started laying track almost a 1/4 century ago. It's a Korean knock-off -- in terms of looks -- of the very nice Fluke meters ( it's a UEI DM 383). While not a Fluke, it's built tough and wasn't real cheap, IIRC about $80, but worth every penny in terms of service and endurance.

Mike Lehman

Urbana, IL

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Posted by richhotrain on Tuesday, April 28, 2015 2:37 PM

OK, I have my car pointed in the direction of my local Harbor Freight store.

So, now, the only question is, which multimeter?

http://www.harborfreight.com/catalogsearch/result/?q=multi+meter

Rich

Alton Junction

  • Member since
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Posted by rrinker on Tuesday, April 28, 2015 2:52 PM

 Look for a coupon, the $5.99 one can usually be had for $1.99 or sometimes even free. That's all you really need for model railroading - I have about 4 of them around the house and in my car. I paid $1.99 for most of mine - when one finally killed the batteries, it actually cost more for repalcement batteries than Ipaid for the meter. I kept it, maybe I'll hook a power supply up to it and use it as a bench meter, but I do have an old fancy Fluke benchtop one. I just bought another HF meter to repalce the one with the dead batteries. Some of those Chinese places on eBay sell the batteries in large quantities (like they do LEDs) at prices which ork out to be about 10 cents a battery, so even if half of them are DOA it's still a bargain - if I had enough things that use those type of batteries.

 ANyway, the cheapy is all you need.

                          --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
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Posted by richhotrain on Tuesday, April 28, 2015 3:01 PM

OK, I see three of them for $5.99 but no coupon.  Where is it?

Rich

Alton Junction

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Posted by maxman on Tuesday, April 28, 2015 3:52 PM

I got the meter last week. Looks like this week's free item is a tape measure.  They seem to cycle between the free items every couple of weeks.

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Posted by richg1998 on Tuesday, April 28, 2015 4:21 PM

I have four. One in the car. Twelve volt system.

One with a few components for a DCC amp meter.

Two for general mrr use.

Very good meters. Only those who don't use them, don't like them.

I made three foot long test leads and a set with alligator clips.

Probably cost as much as a couple meters but good test leads help. I have done home experimenting with electronics for years.

I compared these meters to a Fluke a few years ago and maybe 2 percent error. Too much error for rivet counters. lol

Suggestions.

http://www.trainelectronics.com/Meter_HF/index.htm

http://www.trainelectronics.com/Meter_Workshop/index.htm

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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Posted by RR_Mel on Tuesday, April 28, 2015 4:48 PM

richhotrain

OK, I have my car pointed in the direction of my local Harbor Freight store.

So, now, the only question is, which multimeter?

http://www.harborfreight.com/catalogsearch/result/?q=multi+meter

Rich

 

 

 
The cheapo!
My wife picked me up a spare one for free today with the purchase of a package of heat shrink.
 
HF Meter 2
 
Mel
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Posted by rrinker on Tuesday, April 28, 2015 5:31 PM

 What I want to do with a bunch of them is add Rob Paisley's DCC amp circuit and make panel meters out of them - free meter, a few bucks for Rob's circuit, and a cheap wall wart to power the meter - infinitely cheaper than a RRAmpmeter. Though there are some nice inexpensive millivolt meters on eBay that would also do the job of being the readout - they are more expensive than the HF meter though.

                         --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    July 2008
  • 1,206 posts
Posted by mfm37 on Tuesday, April 28, 2015 7:11 PM

I was using my Radio Shack DVM testing continuity on a 120AC circuit. Someone inadvertently through the main breaker on without warning. Meter has been flaky ever since.

Martin Myers

  • Member since
    January 2009
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Posted by RR_Mel on Tuesday, April 28, 2015 7:36 PM

rrinker

 What I want to do with a bunch of them is add Rob Paisley's DCC amp circuit and make panel meters out of them - free meter, a few bucks for Rob's circuit, and a cheap wall wart to power the meter - infinitely cheaper than a RRAmpmeter. Though there are some nice inexpensive millivolt meters on eBay that would also do the job of being the readout - they are more expensive than the HF meter though.

                         --Randy

 

Randy
 
I bought a cheapo digital meter off eBay for my control panel for less than $5.  Works great! 
 
Check out this one.
 
This is the accessory portion of my control panel.
 Control Panel
 
I think I gave about $5 for that volt meter.  It came as a flush mount with a nice bezel.  It takes 9 volts to power it, a $3 wall wart takes care of that.
 
Mel
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    August 2011
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Posted by narrow gauge nuclear on Thursday, May 7, 2015 11:53 PM

Have two boxes of those Harbor Freight meters, (~26)  They were a super offer here over the last summer and I collected flyers from my friends, plus my own and sent my wife and I each day for about 2 weeks for the $1.99 meters until I got what seems like the right amount of backup meters.

As an electronics engineer, they are great meters that never need repair, only replacement.  I still pick one up now and then when a flyer hits.  It is rare to see them offered at that price lately.

I regularly forget to exchange the leads or knob  from current measurement to voltage and blow the 500 ma fuses with great frequency.  As it became so frequent and I got tired of soldering in a new minature pigtail fuse,  I just mounted a common 3AG cartridge fuse holder externally on the side of the meter.  I found about 8 boxes of 5 fuses, 3AG 600ma, at a hamfest for $1.00 for all and so, now, I can immediately fix the blown fuse issue.

Richard

If I can't fix it, I can fix it so it can't be fixed

  • Member since
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  • From: Dearborn Station
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Posted by richhotrain on Friday, May 8, 2015 6:13 AM

narrow gauge nuclear

I regularly forget to exchange the leads or knob  from current measurement to voltage and blow the 500 ma fuses with great frequency.  As it became so frequent and I got tired of soldering in a new minature pigtail fuse,  I just mounted a common 3AG cartridge fuse holder externally on the side of the meter. 

Ahhh, finally, someone else with blow fuses.  I plead innocent to misusing my Radio Shack multimeter.  I am convinced that it is a lemon.
 
Rich

Alton Junction

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